1. Field of the Invention
The invention relates to an arrangement of at least three holding, centering or knife jaws, lying in a plane, in cutting and/or stripping apparatuses for rod-like or cable-like articles.
It also relates to an arrangement of at least three holding, centering or knife jaws, lying in a plane, in cutting and/or stripping apparatuses for rod-like or cable-like articles, which jaws are each displaceable or pivotable in the direction of a first straight line, and adjacent first straight lines make a first angle with one another. The position of the first straight line is defined by the direction of displacement or by the position of a tangent on the outermost swivel radius of each jaw. In the latter case, the outermost swivel radius is determined by the distance from a center of rotation to that point of each jaw which is farthest away from the said center of rotation.
For the purposes of the present invention, the term line also means a curved line. Such an arrangement is used, for example, for stripping wires.
2. Background Art
Corresponding arrangements are available in a very wide variety of embodiments: German Offenlegungsschrift 2122675 shows four knife jaws, two of which lie in a plane while the other two knife jaws lie in a parallel plane, in each case opposite one another. Hence, a rectangular area is formed between these four knife jaws, the said area being surrounded by blades. This rectangle is enlarged when the opposite knife jaws are pushed apart. By pushing the knives together, the rectangle is made smaller. Furthermore, a control is provided which synchronizes the movement of all four knives so that the rectangle always has sides of equal length. Such knife arrangements have a large variable diameter range and are of a simple design.
A similar arrangement is disclosed in Swiss Patent 651426 (British Patent 2063580). The embodiment is in principle very similar to the embodiment described in the German Offenlegungsschrift, but the cutting line or the contact line of the knife jaws is curved.
The entire content of these publications as well as the content of the publications cited below is to be regarded as part of the disclosure of the present invention.
The French Patent 2282179 describes a knife arrangement having radially guided knives whose cutting line is at an angle of about 45.degree. to the direction of displacement.
As a result of the substantial automation of production lines, there is a constant requirement for increased stability of the knife jaws. It is necessary to take into account in particular the fact that the stripping processes often involve different diameters. The stability of the known knife jaws described above is limited because, even when the cables to be stripped are of different diameters, it is always one and the same part of the knives which bears the load or at least part of the load. For example, it is clear from FIG. 12 of the German Offenlegungsschrift and from FIG. 2 of the Swiss Patent that, even when the knives are pushed together or pulled apart, it is always the middle region of the knives which performs the cutting function. Hence, the middle region is subject to great wear while the edge regions may suffer scarcely any wear. In the case of the French Patent, the same applies to the frontmost tip of the jaws. In the case of holding or centering arrangements, "grinding" of the holding or centering surfaces occurred in a similar manner and after some time had an adverse effect on the precision. This also applies to the arrangement according to U.S. Pat. No. 1,597,460, which arrangement, however, only has two knife jaws and therefore does not permit centering of the cables.
Knife arrangements have also been disclosed, for example in U.S. Pat. No. 3,892,145, which have rotatable knives whose service lives are also longer than those of previously known static knives. A disadvantage, however, is that these knives have only a slightly variable diameter range and furthermore cannot be closed to extremely small diameters, as is the case with conventional arrangements. Furthermore, such knife arrangements require additional sliding bearings and may require expensive rotary drives and have therefore not become established in practice.
German Patent 28 48 445 (U.S. Pat. No. 4,327,609) and, for example, also European Offenlegungsschrift 146 397 disclose arrangements which employ different points but, like some of the constructions mentioned above, lie back to back or in two planes. Consequently, when cutting into a cable, the latter is perforated along its circumference, viewed in the axial direction, along different lines, which can lead to uneven tearing during subsequent stripping; this is particularly the case when the knife blades are provided with a chamfer, as is essential for increasing the stability.